(a)++Chromosomes

Chromosomes are a thread-like structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes (C//hromosome).In a normal human cell there are 46 chromosomes. Chromosomes are concidered to be very important, as they provide information on features and characteristics (trait) of each living organism.// //definitions of some words://
 * What are chromosomes? **

//__Trait:__// a characteristic or property of some object __//nucleic acids://__ //nucleic acids are made up of// //nucleotides, nucleic acid can take form in DNA or RNA, containing genetic information important for cellular function.// (From <[]>)

__//Nucleotides://__ a group of molecules that, when linked together, form the building blocks of DNA or RNA: composed of a phosphate group, the bases adenine, cytosine, guanine, and thymine.

media type="youtube" key="LFBEL1ifqlg" height="408" width="546" (from [])
 * Below is a video of the chromosome structure:**

A karyotype is a picture of the chromosomes an individual cell has. A karyotype gives information about the number of chromosomes that a person has as well as the structure and sex of each chromosome. A karyotype is used to check for chromosome abnormalities (//Karyotype//). Below is a human karyotype- arranged in pairs and the 23rd pair in an X and Y chromosome. (from [])
 * What are Karyotypes? **

Below is a video showing how different karyotypes affect you media type="youtube" key="a5yzRRvROpE?version=3" height="360" width="640" (From: []) The study of the sets of chromosomes can also be called Karyology. These chromosome are organized in a standard format that is known as a karyogram (or idiogram). These chromosomes are in pairs and are ordered by size and positions of the centromere. When observing karyotypes there are six different areas that are observed and compared:
 * 1) Difference in absolute sizes of the chromosomes.
 * 2) Difference in the position of entromeres
 * 3) Difference in relative size of chromosomes
 * 4) Difference in basic number of chromosomes
 * 5) Difference in number and position of satellites (small bodies attacked to a chromosome by a thing thread)
 * 6) Difference in degree of distribution of heterochromatic (a tightly packed form of DNA) regions

So, in conclusion, a full karyotype must include the number, type, shape and banding of the chromosomes, as well as other cytogenetic information (//Karyotype//).

The karyotype can be used for different situations an example would be to diagnose Down syndrome. Since karyotype gives information about the number of chromosomes and their information (arrangement etc..), by looking at it conditions like Down syndrome can be diagnosed. Usually there problems are caused by the number of the chromosomes or translocation. So a karyotype for down syndrome would have an extra number of 21 chromosome for a total of 47 chromosomes, instead of 46 (//Down Syndrome//). (from http://geneticdisorderinfo.wikispaces.com/Down+Syndrome)
 * **Example of how Karyotype can be used:**

NONDISJUNCTION is when there are too many or too few chromosomes. Normally, during meiosis, the type of cell division that produces sex cells, each cell recieves one of each choromosome. During fertilization (when the egg and sperm fuse together) the zygote recieves two copies of each choromosome. This is the normal number which provides proper development. If the choromosomes are not distributed correctly into the two daughter cells, than one daughter cell will have twice the number of copies of that chromosome, and the other daughter cell will have none. This is called NONDISJUNCTION. If these cells are fertilized, they result in abnormalities in the offspring such as down's syndrome, Turner's syndrome (when there are too little chromosomes), and Klinefelter's syndrome (when there are too many chromosomes).


 * WORK CITED: **